Airbag

So, building on what others have said here, I offer the following possibility. I see Airbag as a tribute song about the amazing, unstoppable and mysterious powers of gasses. Yes, you read that right: it's basically a hero-worship song about gasses. Bear with me, and I'll explain.

1) Jackknifed juggernaut is definitely describing a tractor-trailer truck (lorry). "Jackknifed" is a very specific term in this context that describes a dangerous moving condition where the trailer pushes past the tractor and their connecting joint forces the tractor up against the side of the trailer while facing in the wrong direction (kinda looks like a jack knife pulled slightly out of its sheath, hence the term). At this point, the vehicle's motion is completely out of control, and a crash or flip-over becomes an extremely likely outcome. In the next world war, this semi would probably be carrying liquefied gas fuel or perhaps even chemical weapons that are also gasses. In addition, those trucks almost always have pressurized air brakes and horns - gasses again.

2) The neon sign, scrolling up and down may be very slowly leaking the compressed gas that glows in bright colors when electricity is passed through it. I When the pressure of the gas in those tubes drops due to a slow leak, greater distance between the gas atoms means that the electricity takes a more circuitous path through the gas, resulting in a slow, serpentine scrolling of the light that's generated.

3) "In a deep, deep sleep of the innocent" describes the peaceful state of the compressed gas charge that spends its entire existence quietly and unknowingly waiting to be violently discharged into a car's airbag upon impact.

After each of the descriptive lyrics above, the phrase "I am born again" is used. In my mind's eye, I see three different types of transformation being undergone by gasses: 1) A violent explosion and combustion of the gas carried by the jackknifed juggernaut when it crashes under combat conditions. 2) A slow leak that permits the neon atoms to slowly leave their compressed brothers. 3) The lightning-fast violent expulsion of the airbag's compressed gas charge. While they are transformed in each of the above instances, in no case are any of the gasses destroyed, hence the "born again" lyric.

The chorus "In an interstellar burst, I am back to save the universe" is also talking about gasses. Stars, the sustaining sources of the energy that powers all life in our universe, are composed mainly of massive quantities of simple gases which fuel nuclear fusion reactions on an enormous scale. Light, charged particles and other radiation stream out from stars, but the only bursts that I know of come from solar flares that result in the periodic ejection of some of the star's gasses at very high speed. Some of these interstellar bursts of gas may eventually collect together to form nebulae, which are basically just huge (light-years wide) clouds of gas out in space. In these nebulae, stars are actually born, beginning the cycle of everything all over again, thereby "saving the universe."

The punchline of the song for me comes in the last lyric, and it always makes me smile: "In a fast German car/I'm amazed that I survived/An airbag saved my life." The life saved is not that of the passengers or driver of the car, but is (amusingly) that of the compressed gas charge that would otherwise have been blown away in all directions if not for the saving grace of the airbag that instantly inflates to capture it. :-)

Long explanation, I know, but I really love the song, so I've thought way too much about it....